A smart coal grinding and pulverizing system for thermal power plants

Abstract

The present invention discloses an intelligent coal grinding and pulverizing system for a thermal power plant, which comprises a coal aperture optimization module for a coal mill feed port, a coal mill air volume adjustment module and a coal mill outlet air-powder mixture temperature control module; the coal mill feed port coal aperture optimization module is used for optimizing the aperture of coal blocks at the feed port of the coal mill to ensure that the coal blocks obtained after entering the coal mill are of the optimal grinding block size; the coal mill air volume adjustment module is used for controlling the primary air flow of the coal mill according to the coal aperture size required for discharge from the coal mill; the coal mill outlet air-powder mixture temperature control module utilizes boiler unit and pulverizing system analysis to control the temperature at the coal mill outlet for coals with different volatile contents; the present invention improves the unit's rapid load-carrying capacity, the quality of coordinated parameter control and the economy of the unit's operation through intelligent control of the wind speed, wind pressure and air outlet temperature of the coal mill.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent control technology, and particularly relates to an intelligent coal grinding and pulverizing system for a thermal power plant. Background Art

[0002] Ball mills are widely used in coal-fired power plants in my country. However, these critical equipment still mostly operates under primitive conditions, relying on human judgment and manual operation. During operation, coal blockage, overheating, coal leakage, air leakage, and insufficient coal are common, sometimes even causing equipment damage and unit shutdown, resulting in significant economic losses for the power plant. More importantly, coal mills are a major consumer of power in power plants, accounting for approximately 20% of the plant's total electricity consumption. Because these mills are still manually controlled, their automation level is low, reducing their efficiency. Summary of the Invention

[0003] The purpose of the present invention is to provide an intelligent coal grinding and pulverizing system for a thermal power plant, which improves the unit's rapid load-carrying capacity, the quality of coordinated parameter control, and the economy of the unit's operation through intelligent control of the wind speed, wind pressure, and outlet temperature of the coal mill.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solutions: a smart coal grinding and pulverizing system for a thermal power plant, comprising a coal pulverizer inlet coal aperture optimization module, a coal pulverizer air volume adjustment module, and a coal pulverizer outlet air-pulverizer mixture temperature control module;

[0005] The coal pore size optimization module for the coal mill inlet is used to optimize the pore size of the coal blocks at the coal mill inlet to ensure that the coal blocks obtained after entering the coal mill are of the optimal grinding coal block size;

[0006] The coal mill air volume adjustment module is used to control the coal mill primary air flow rate to be adjusted back and forth according to the coal pore size required for the coal mill to be discharged;

[0007] The air-powder mixture temperature control module at the coal mill outlet utilizes boiler unit and pulverizing system analysis to control the temperature at the coal mill outlet for coals with different volatile contents.

[0008] Preferably, the coal aperture optimization module at the coal mill feed port works on coal block sorting and combustion analysis, wherein the coal block sorting is performed by using a coal block sorter to sort various coals entering the coal mill to separate coal blocks of different particle size grades.

[0009] Preferably, the combustion analysis includes burning each coal block of each particle size, and detecting the combustion products and the heat released by the combustion during the combustion process.

[0010] Preferably, the combustion products are detected by using an air concentration detector, and the heat meter uses the heat generated to count the time it takes for 1 cubic meter of water to burn at 25-100°C. After the statistics, the combustion heat of the combustion product machine is used to comprehensively select the corresponding coal block particle size, and then the optimal particle size of coal blocks with different element contents is selected.

[0011] Preferably, the coal mill air volume adjustment module includes a flow meter and a blower. The flow meter extends into the coal mill feed port. A control valve is connected between the flow meter and the blower. At the same time, a speed regulating valve is installed on the blower. The speed regulating valve controls the speed of the motor inside the blower. When the flow rate monitored by the flow meter is greater than or less than a preset value, the flow meter excites an electrical signal to the control valve, and the control valve controls the speed regulating valve on the blower for adjustment.

[0012] Preferably, the pulverizer outlet air-powder mixture temperature control module first reads the boiler unit parameters and selects the corresponding boiler based on different types of coal, including sulfur-containing coal, nitrogen-containing coal, etc.

[0013] Preferably, the optimal temperature of the air-powder mixture at the pulverizer outlet is as follows: the pulverizer outlet temperature for coal with a volatile matter of less than 38% is ≥90°C; the pulverizer outlet temperature for coal with a volatile matter of more than 38% is ≥75°C, so that the opening of the hot air door at the inlet of the running pulverizer is greater than 80%, and the opening of the cold air door at the inlet is less than 20%.

[0014] Preferably, the wall temperature of the secondary air ring nozzle inside the boiler assembly is less than 850°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Set up the coal aperture optimization module at the pulverizer inlet to optimize the particle size of coal blocks with different element contents, and then control the coal block aperture size at the pulverizer discharge point to ensure that the coal blocks processed by the pulverizer are of the optimal grinding block size, thereby improving the coal grinding efficiency.

[0017] 2. Through intelligent adjustment of wind speed and pressure, the primary air pressure is optimized and controlled with reference to the maximum opening of each mill's primary air damper. On the basis of ensuring load adjustment capability and pipe blockage treatment capability, the primary air pressure is optimized to avoid unnecessary wind resistance, improve the efficiency of coal entering the mill, and maintain safe and stable operation of the boiler.

[0018] 3. Set up the air-powder mixture temperature control module at the coal mill outlet to control the temperature of the air-powder mixture at the coal mill outlet and appropriately increase the coal mill outlet temperature. Without affecting the safe operation of the coal mill, it can also increase the coal mill output and reduce the unit consumption of pulverizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1This is a schematic block diagram of the system connection of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] See also Figure 1 , the present invention provides a technical solution: a smart coal grinding and pulverizing system for a thermal power plant, comprising a coal pulverizer inlet coal aperture optimization module, a coal pulverizer air volume adjustment module, and a coal pulverizer outlet air-powder mixture temperature control module;

[0022] The coal pore size optimization module for the coal mill inlet is used to optimize the pore size of the coal blocks at the coal mill inlet to ensure that the coal blocks obtained after entering the coal mill are of the optimal grinding coal block size;

[0023] The coal mill air volume adjustment module is used to control the coal mill primary air flow rate to be adjusted back and forth according to the coal pore size required for the coal mill to be discharged;

[0024] The air-powder mixture temperature control module at the coal mill outlet utilizes boiler unit and pulverizing system analysis to control the temperature at the coal mill outlet for coals with different volatile contents.

[0025] Specifically, the coal aperture optimization module at the pulverizer inlet works on coal block sorting and combustion analysis. The coal block sorting is performed by using a coal block sorter to sort various coals entering the pulverizer and select coal blocks of different particle size grades.

[0026] Specifically, the combustion analysis includes burning each coal block of each particle size and detecting the combustion products and the heat released during the combustion process.

[0027] Specifically, an air concentration detector is used to detect the combustion products, and the heat meter uses the heat generated to count the time it takes for one cubic meter of water to burn at 25-100°C. After the statistics, the combustion heat of the combustion products and the corresponding coal block particle size are selected based on the combination of the two, and then the optimal particle size of coal blocks with different element contents is selected.

[0028] In the above embodiment, since the coal blocks inside the thermal power plant usually have different element contents, the optimal particle size statistics of various coal blocks are performed in advance when entering the pulverizer, and then the pulverizer is controlled to output the corresponding particle size. By calculating the selection of different particle sizes of different coal blocks for combustion, the optimal coal particle size is selected, thereby improving the efficiency of subsequent coal combustion in the thermal power plant.

[0029] Specifically, the coal mill air volume regulation module includes a flow meter and a blower. The flow meter extends into the coal mill inlet. A control valve is connected between the flow meter and the blower. At the same time, a speed regulating valve is installed on the blower. The speed regulating valve controls the speed of the motor inside the blower. When the flow rate monitored by the flow meter is greater than or less than the preset value, the flow meter excites an electrical signal to the control valve, and the control valve controls the speed regulating valve on the blower for adjustment.

[0030] The velocity of the air-powder mixture in the pulverized coal pipeline should be maintained within a certain range. If the flow rate is too low, the pulverized coal will be deposited in the pulverized coal pipeline, causing pulverized coal blockage. If the flow rate is too low, the ignition point will move closer to the burner nozzle, causing burnout of the burner nozzle. If the flow rate is too high, the pulverized coal particles brought into the furnace will be too coarse, slowing down the ignition. In severe cases, the pulverized coal will not be completely burned, resulting in serious slagging. Fluctuations or disturbances in the primary air flow of the pulverizer will seriously affect the amount of pulverized coal fed into the furnace, which will have an adverse effect on maintaining stable combustion in the boiler. Controlling the primary air flow of the pulverizer within a reasonable range is a basic requirement for maintaining safe and stable operation of the boiler and is a prerequisite for achieving optimized operation of various boiler parameters.

[0031] Specifically, the air-powder mixture temperature control module at the pulverizer outlet first reads the boiler unit parameters and selects the corresponding boiler based on different types of coal, including sulfur-containing coal, nitrogen-containing coal, etc.

[0032] Specifically, the optimal temperature of the air-powder mixture at the pulverizer outlet is as follows: the pulverizer outlet temperature for coal with a volatile matter of less than 38% is ≥90°C; the pulverizer outlet temperature for coal with a volatile matter of more than 38% is ≥75°C, and the opening of the hot air door at the inlet of the running pulverizer is greater than 80%, and the opening of the cold air door at the inlet is less than 20%.

[0033] Specifically, the wall temperature of the secondary air ring nozzle inside the boiler assembly is less than 850°C.

[0034] The temperature of the air-pulverized coal mixture at the mill outlet is the primary factor influencing the ignition and stable combustion of pulverized coal. A higher mill outlet temperature results in less moisture in the pulverized coal, lowering the latent heat of vaporization and ignition heat required for ignition, making the pulverized coal more suitable for ignition and stable combustion. Increasing the mill outlet temperature also facilitates the drying process of the pulverized coal, improves mill output, and reduces pulverizing unit consumption. However, the mill outlet temperature cannot be too high, as excessively high temperatures can cause volatile substances in the pulverized coal to precipitate, increasing the risk of mill deflagration and fire. Furthermore, high mill outlet temperatures can affect the safe and stable operation of the mill lubricating oil system. Appropriately increasing the mill outlet temperature does not affect the safe operation of the mill, but can increase mill output and reduce pulverizing unit consumption.

[0035] Through in-depth testing and analysis of boiler units and pulverizing systems, we absorbed the successful experience of raising the outlet temperature of coal mills for the same type of units for different volatile coal types. Based on the commonly used coal types in power plants, we raised the outlet temperature of the coal mill while ensuring the safety of the boiler units, thereby reducing the boiler exhaust temperature and improving boiler efficiency.

[0036] From the above description, it can be seen that the present invention has the following beneficial effects: through intelligent control of the wind speed, wind pressure and outlet temperature of the coal mill, the unit's rapid load-carrying capacity, coordinated parameter control quality and unit operation economy are improved.

[0037] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0038] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A smart coal grinding and pulverizing system for a thermal power plant, characterized in that: It includes a coal pore diameter optimization module for the coal mill inlet, a coal mill air volume adjustment module, and a coal mill outlet air-powder mixture temperature control module; The coal pore size optimization module for the coal mill inlet is used to optimize the pore size of the coal blocks at the coal mill inlet to ensure that the coal blocks obtained after entering the coal mill are of the optimal grinding coal block size; The coal mill air volume adjustment module is used to control the coal mill primary air flow rate to be adjusted back and forth according to the coal pore size required for the coal mill to be discharged; The air-powder mixture temperature control module at the coal mill outlet uses the boiler unit and pulverizing system analysis to control the temperature at the coal mill outlet for coals with different volatile contents. The coal pore size optimization module for the coal mill feed port includes coal lump sorting and combustion analysis. The coal lump sorting is performed by using a coal lump sorter to sort various coals entering the coal mill and select coal lumps of different particle sizes. The air-powder mixture temperature control module at the pulverizer outlet first reads the parameters of the boiler unit and selects the corresponding boiler based on different types of coal; the optimal temperature of the air-powder mixture at the pulverizer outlet is as follows: the pulverizer outlet temperature for coal with a volatile matter of less than 38% is ≥90°C; the pulverizer outlet temperature for coal with a volatile matter of more than 38% is ≥75°C, so that the opening of the hot air door at the inlet of the running pulverizer is greater than 80%, and the opening of the cold air door at the inlet is less than 20%.

2. The intelligent coal grinding and pulverizing system for a thermal power plant according to claim 1, characterized in that: The combustion analysis includes burning each coal block of each particle size and detecting the combustion products and the heat released during the combustion process.

3. The intelligent coal grinding and pulverizing system for a thermal power plant according to claim 1, characterized in that: The combustion products are detected by using an air concentration detector, and the heat meter uses the heat generated to count the time it takes for 1 cubic meter of water to burn at 25-100°C. After the statistics, the combustion heat of the combustion products and the corresponding coal block particle size are selected based on the combination of the two, and then the optimal particle size of the coal blocks with different element contents is selected.

4. The intelligent coal grinding and pulverizing system for a thermal power plant according to claim 1, characterized in that: The coal mill air volume adjustment module includes a flow meter and a blower. The flow meter extends into the coal mill feed port. A control valve is connected between the flow meter and the blower. At the same time, a speed regulating valve is installed on the blower. The speed regulating valve controls the speed of the motor inside the blower. When the flow rate monitored by the flow meter is greater than or less than a preset value, the flow meter excites an electrical signal to the control valve, and the control valve controls the speed regulating valve on the blower for adjustment.

5. The intelligent coal grinding and pulverizing system for a thermal power plant according to claim 1, characterized in that: Coal types include sulfur-containing coal and nitrogen-containing coal.

6. The intelligent coal grinding and pulverizing system for a thermal power plant according to claim 1, characterized in that: The wall temperature of the secondary air ring nozzle inside the boiler assembly is less than 850℃.

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